if a latecomer to Salah catches the third Rak`ah of the `isha' (Night) congregational Prayer, how should he make up
for the missed Rak`ahs? Should he recite subvocally or loudly?
A latecomer should perform two Rak`ahs according to the consensus of scholars. He should recite only Al-Fatihah silently according to the correct view of scholars, for what the latecomer prayed with the Imam is considered the first part of his Salah and what he prays after the end of congregational prayer forms the last of his Salah. The apparent meaning of the following Hadith lends support to this notion:
When you come for Salah, be tranquil. Then, pray what you can (with Imam) and complete what you miss.
(Part No. 7; Page No. 324) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.